Shell's Perdido platform may provide lessons in innovation

Published 7:00 pm, Saturday, May 9, 2009

There was a time when 1,500 feet of water was considered deep for a floating oil and gas platform.

That's so last decade.

Now Royal Dutch Shell's Perdido is floating in 8,000 feet of water 200 miles south of Freeport. It's a 50,000-ton structure taller than the company's own U.S. headquarters in downtown Houston.

And last year Perdido drilled and completed the world's deepest offshore well, drawing hydrocarbons from a wellhead nearly two miles below the water's surface.

The technical, financial and even political challenges of such complex projects were among the main topics at the annual four-day Offshore Technology Conference last week at Reliant Park.

Shell didn't plan elaborate presentations about Perdido.

"We weren't going to go out there and start claiming any success if we haven't finished the project," project manager Dale Snyder said. "We're targeting OTC in 2010."

Still, Perdido's achievements will loom large this year. Lessons learned from its design and deployment will be included in some of technical sessions planned for the week, while revelations from other sessions likely will be absorbed by Shell engineers for consideration as the project moves forward.

Perdido's depth of operation matches the Anadarko Petroleum-operated Independence Hub, which earned the title of world's deepest platform in mid-2007 when it started pumping natural gas in 8,000 feet of water about 185 miles from New Orleans,

But Perdido will pump oil as well as natural gas from one of the deepest reservoirs in the Gulf of Mexico - in rock and salt 38 million to 66 million years old known as the Lower Tertiary trend.

New standards

When companies venture out farther and deeper, they often break new technological ground.

"Every time you take on one of these technology challenges, you set a new standard," said Russ Ford, Shell's technology vice president for the Americas. "This is the kind of stuff we're going to do right now. The industry's got to find a way to produce this stuff reliably, safely and economically."

The foundation of the Perdido structure is a cylindrical floating spar that extends hundreds of feet below the surface of the Gulf. Atop the spar are decks with oil and gas processing facilities and a drilling rig as well as crew quarters. Extending down from the spar to the sea floor are mooring lines and pipes called risers.

The nearest other platform is Exxon Mobil's Hoover Diana, 60 miles to the north.

Far from anywhere

Snyder said Perdido's remote location required a string of innovations to handle rough seas, the great water depth and reservoirs with low pressure and low temperatures under massive weight of water.

Perdido had to be compact to economically produce 130,000 barrels of oil equivalent per day, Snyder said. Shell set strict weight limits on everything, reducing the cost of steel and other raw materials for the multi-billion-dollar platform.

"We knew that if we didn't do anything new, and if we did it the way everybody else does it, this was going to be a massive platform," he said.

Fewer risers

Other platforms have a riser for each well. Perdido will have six risers - one for drilling and five that serve multiple wells. These risers connect to seafloor structures called manifolds, which in turn have lines leading to 22 seafloor wells across an area the size of Houston. One of those wells is the one that became the world's deepest last year, at 9,627 feet.

Using fewer risers helped lower construction costs.

Topside, a steel blast wall separates processing units from living quarters, of- fices and emergency systems, which are on the same deck. Larger platforms typically put those elements on separate decks.

But the most notable innovation will compensate for pressure too low to boost oil and gas past the seafloor.

The manifolds separate water from oil and gas at the seafloor, making it less difficult to pump the hydrocarbons to the surface. Removing the water also will keep ice from clogging lines.

"It may be a design that other people look at," said Matt Pickard, an analyst with Quest Offshore.

Snyder noted that Perdido started with Shell's 1996 purchase of a lease. At that time, Shell was installing its Mars platform in 3,000 feet of water about 130 miles southeast of New Orleans.

The industry didn't have the technology to drill and put platforms in another 5,000 feet of water. Shell discovered oil at Perdido in 2002, worked to perfect the technology and sanctioned the project in 2006.

"You get an idea of the timeline involved and how difficult it is to do this thing," he said. "To think that you buy the lease and OK, where's the oil? It's crazy. It's certainly something I think people have got no appreciation for."